| ON cone bipolar cell | Hartveit (H) | For many cells of types CB5-CB9, kainate did not evoke a short-latency response, but indirectly mediated responses were sometimes observed during longer-lasting application of kainate. These indirect responses were slow in onset, reversed close to and followed changes in ECl, and could be blocked by a combination of picrotoxin and 3-APMPA. These characteristics were identical to those described above for OFF cone bipolar cells and to those observed previously for rod bipolar cells (Hartveit 1996b). In addition, a few cells responded to kainate with an outward current at -70 mV, typical for APB-like responses. On the basis of these results, one would expect that CB5-CB9do not express functional (conductance increasing) ionotropic glutamate receptors and therefore would correspond physiologically to ON cone bipolar cells. | is included | | ...some cells (among CB5-CB9) did not display short-latency responses to kainate. Other cells of the same types (CB5-CB8), however, displayed short-latency kainate responses, but the evoked current either could not be reversed or reversed at positive potentials. I propose that these cells (CB5-CB9) are ON cone bipolar cells and that the short-latency kainate responses are mediated via gap junctions with AII amacrine cells. | Hartveit E. | Mihail Bota |
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